Ticket #7045: mov_pixeldensity.patch

movenc.c

@@ -76 +76 @@
     { "delay_moov", "Delay writing the initial moov until the first fragment is cut, or until the first fragment flush", 0, AV_OPT_TYPE_CONST, {.i64 = FF_MOV_FLAG_DELAY_MOOV}, INT_MIN, INT_MAX, AV_OPT_FLAG_ENCODING_PARAM, "movflags" },
     { "global_sidx", "Write a global sidx index at the start of the file", 0, AV_OPT_TYPE_CONST, {.i64 = FF_MOV_FLAG_GLOBAL_SIDX}, INT_MIN, INT_MAX, AV_OPT_FLAG_ENCODING_PARAM, "movflags" },
     { "skip_sidx", "Skip writing of sidx atom", 0, AV_OPT_TYPE_CONST, {.i64 = FF_MOV_FLAG_SKIP_SIDX}, INT_MIN, INT_MAX, AV_OPT_FLAG_ENCODING_PARAM, "movflags" },
+    { "write_pixeldensity", "Write pixeldensity metdata for HiDPI videos in QT", 0, AV_OPT_TYPE_CONST, {.i64 = FF_MOV_FLAG_PIXELDENSITY}, INT_MIN, INT_MAX, AV_OPT_FLAG_ENCODING_PARAM, "movflags" },
     { "write_colr", "Write colr atom (Experimental, may be renamed or changed, do not use from scripts)", 0, AV_OPT_TYPE_CONST, {.i64 = FF_MOV_FLAG_WRITE_COLR}, INT_MIN, INT_MAX, AV_OPT_FLAG_ENCODING_PARAM, "movflags" },
     { "write_gama", "Write deprecated gama atom", 0, AV_OPT_TYPE_CONST, {.i64 = FF_MOV_FLAG_WRITE_GAMA}, INT_MIN, INT_MAX, AV_OPT_FLAG_ENCODING_PARAM, "movflags" },
     { "use_metadata_tags", "Use mdta atom for metadata.", 0, AV_OPT_TYPE_CONST, {.i64 = FF_MOV_FLAG_USE_MDTA}, INT_MIN, INT_MAX, AV_OPT_FLAG_ENCODING_PARAM, "movflags" },
@@ -3118 +3119 @@
     return 0;
 }
 
+static int mov_write_pixeldensity_meta_tag(AVIOContext *pb, MOVMuxContext *mov, MOVTrack *track, AVFormatContext *s)
+{
+    int size = 0;
+    int64_t pos = avio_tell(pb);
+    avio_wb32(pb, 0); /* meta atom size */
+    ffio_wfourcc(pb, "meta");
+
+    /* Metadata atom information as described in
+     * https://developer.apple.com/library/archive/documentation/QuickTime/QTFF/Metadata/Metadata.html#//apple_ref/doc/uid/TP40000939-CH1-SW9
+     */
+    avio_wb32(pb, 33); /* hdlr atom size: size (4) + 'hdlr' (4) + version/flags (4) + predefined (4) + 'mdta' (4) +
+                          reserved (3*4) + name (1) = 33 */
+    ffio_wfourcc(pb, "hdlr");
+    avio_wb32(pb, 0); /* version (1 Byte) and flags (3 Bytes), must be zero */
+    avio_wb32(pb, 0); /* "predefined", must be zero */
+    ffio_wfourcc(pb, "mdta");
+    avio_wb32(pb, 0); /* Reseverved, uint32_t[3] */
+    avio_wb32(pb, 0);
+    avio_wb32(pb, 0);
+    avio_w8(pb, 0); /* Empty name (NULL-terminated) */
+
+    avio_wb32(pb, 56); /* keys atom size: size (4) + 'keys' (4) + version/flasgs (4) + entry_count (4) +
+                          keys (32+8) = 56 */
+    ffio_wfourcc(pb, "keys");
+    avio_wb32(pb, 0);      /* version (1 Byte) and flags (3 Bytes), must be zero */
+    avio_wb32(pb, 1);      /* entry count */
+    avio_wb32(pb, 32 + 8); /* key size: size (4) + 'mdta' (4) + strlen(key) */
+    ffio_wfourcc(pb, "mdta");
+    avio_write(pb, "com.apple.quicktime.pixeldensity", 32);
+
+    avio_wb32(pb, 48); /* ilst atom size: size (4) + 'ilst' (4) + value atom size (40) = 48 */
+    ffio_wfourcc(pb, "ilst");
+    avio_wb32(pb, 40); /* value atom size: size (4) + key (4) + data atom (32) = 40 */
+    avio_wb32(pb, 1);  /* metadata key index */
+
+    avio_wb32(pb, 32); /* data atom size: size (4) + 'data' (4) + data_type (4) + locale (4) + value (4 * 4) = 32 */
+    ffio_wfourcc(pb, "data");
+    avio_wb32(pb, 0x1e); /* data type */
+    avio_wb32(pb, 0);    /* locale */
+
+    /* actual data (value): consisting of 4 uint32_t: pixel width, pixel height, display width, display height */
+    avio_wb32(pb, track->par->width);
+    avio_wb32(pb, track->par->height);
+    avio_wb32(pb, track->par->width / 2);
+    avio_wb32(pb, track->par->height / 2);
+
+    size = update_size(pb, pos);
+    return size;
+}
+
 static int mov_write_trak_tag(AVFormatContext *s, AVIOContext *pb, MOVMuxContext *mov,
                               MOVTrack *track, AVStream *st)
 {
@@ -3165 +3216 @@
             mov_write_tapt_tag(pb, track);
         }
     }
+    if (mov->flags & FF_MOV_FLAG_PIXELDENSITY) {
+         mov_write_pixeldensity_meta_tag(pb, mov, track, st);
+    }
     mov_write_track_udta_tag(pb, mov, st);
     track->entry = entry_backup;
     track->chunkCount = chunk_backup;

movenc.h

@@ -258 +258 @@
 #define FF_MOV_FLAG_NEGATIVE_CTS_OFFSETS  (1 << 19)
 #define FF_MOV_FLAG_FRAG_EVERY_FRAME      (1 << 20)
 #define FF_MOV_FLAG_SKIP_SIDX             (1 << 21)
+#define FF_MOV_FLAG_PIXELDENSITY          (1 << 22)
 
 int ff_mov_write_packet(AVFormatContext *s, AVPacket *pkt);